With increasing development, electronic products are more powerful and the sizes thereof are developed toward minimization. In addition to these requirements, the electronic product should have desired quality. For example, scanners are widely used for scanning, opaque objects and processing the image information into analog, or digital forms. Examples of the opaque objects include paper sheets, photographs, etc. In order to achieve better image quality, the components of the scanner should be properly selected and assembled. As known, the type of the light source and the brightness of the reflective light are major factors influencing the image quality of the scanner.
A typical scanner comprises an image sensing module in the lower housing, thereof. The image sensing, module has therein several optical elements including a light source, a reflective mirror, a lens set, and an image sensor such as a charge couple device (CCD). When the scanner is operated, the light emitted by the light source is projected onto an opaque object placed on a scanning, platform, which is typically a glass platform. The light reflected from the scanned object is incident into the image sensing module and reflected by the reflective mirror. By means of the lens set, the light reflected from the reflective mirror is focused on the charge-couple device (CCD) and converted into an electric signal in an analog or digital form.
Referring to FIG. 1, a conventional CCD image sensing module is illustrated. The image sensing module 7 comprises a bush member 8 located at a side thereof. The bush member 8 is integrally formed with the image sensing module 7. The bush member 8 is movably coupled to a shaft 9. By means of some transmission elements such as a transmission drive belt (not shown), the image sensing module 7 is moved in the scanning direction along the shaft 9 so as to realize the image data of the document or picture.
Ideally, the scanning direction of the image sensing module 7 is parallel to the length of the shaft 9, and the reading line of the image sensing module 7 is perpendicular to the scanning direction. Sometimes, however, the reading line direction is deviated from the ideal direction due to an inherent fit tolerance between the image sensing module 7 and the shaft 9. Therefore, the scanning quality is impaired.
In views of the above-described disadvantages resulted from the conventional method, the applicant keeps on carving unflaggingly to develop a reading-line adjusting device of an image scanner according to the present invention through wholehearted experience and research.